Refrigerating apparatus



March 31, 1931. c. F. NYSTROM REFRIGERATING APPARATUS Filed May 13, 1929 l INVENTOR AT'TORNEY Patented Mar. 31, 1931 UNITED STATES PATENT OFFICE CARL IF. NYSTBOH, 0F HANSFIELD, OHIO, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA BEFRIGERATING APPARATUS Application led Hay 13, 1929. Serial No. 362,757.

This invention relates to refrigerating apparatus and particularly to the heat-absorbing units or evaporators embodied in such apparatus.

It is an object of the invention to provide an evaporator the initial displacement of which in the cabinet to be cooled will be relatively .small but which will, at the same time, have a large exposed surface, as compared with its linear dimensions.

Another object is to provide, in an evaporator of this character, a cold storage or brine reservoir which will contain a small amount of brine, thereby providing an evaporator of relatively light weight.

A further object of the invention is to provide a cooling element containinga relatively small amount of brine, the brine being so disposed that a maximum amount thereof is presented to the exposed walls of the container.

A still further object is to provide an evaporator having a brine. reservoir in which the refrigerant'coils and brine container are so disposed as to provide the most effective heat transfer between these elements.

Other objects and advantages of the invention will be apparent from the following description and the accompanying drawings wherein: r y

Figure 1 is a perspective view of an evaporator embodying the invention;

Fig. 2 is a sectional view, taken on the line IIv-H of Fig. 1

Fig. 3 is a sectional view, on an enlarged i scale, taken on the line III- III of Fig. 1 and showing a method of sealing` the end of the brine-containing tube, and

Fig. 4 is a perspective view of the plate provided in the freezing chamber for supporting the ice trays.

Primarily, my invention resides in providing an evaporator comprising two coiled tubes, one disposed inside the other, with the inner tube adapted to convey the refrigerant medium and the outer tube adapted to provide a sealed brine-containing chamber. The diameter of the outer tube should be about twice that ofthe inner tube inorder to provide ample space between the walls of the respective tubes for storingl the brine solution.

When the smaller tube has been inserted within the larger, the whole assembly. is wrapped about a suitably shaped mandrel which may be cylindrical, rectangular, or of any other desired shape. The space interveninfr between the tubes is then filled wi'th a suitabtle cold storage or brine solution of relatively low freezing point, and the ends of the outer tube are sealed, whereby to provide a closed brine-storage chamber. f

The formed coil is then dipped into a suitable soldering bath whereby the individual loops of the coil are firmly fastened to each other thereby providing a comparatively rigid structure. A fixed closure is provided for one end of the freezing chamber formed interiorly of the coil.

A heat-conducting plate may then'be inserted within the freezing chamber for supporting the ice-making trays. The under surface of the plate is preferably provided with parallel rounded depressions extending transversely thereof. The depressions are made sufliciently deep to receive. the protruding portions of the loops upon which the plate rests. By this provision, the plate is brought into maximum thermal contact with the adjacent coil portion, excluding any air between the plate and the coil, and thereby materially increasing the freezing rate of the water contained in the ice-making trays.

The lfree ends of the inner tube are connected to the refrigerant-circulating system, the inlet end of the tube being provided with a suitable pressure-reducing valve.

Referring to the drawings wherein is shown a specic embodiment of the invention, 10 designates the assembled evaporator, formed to provide a freezing chamber 11. The refrigerant coil 12 is disposed within a brine-containin coil 13. I have found that, by making the iameter ofthe brine-contain ing coil approximately twice that of the inner coil, an ample cold-storage reservoir is provided. A collar 14 (Fig. 3) fits snugly over the inner coil and within each of the free ends of the outer coil, as indicated at 15. The collaris soldered' to the two coils, as indicated 12. The outlet end of the coil is indicated at 'l 23 at 16, in order'to provide a sealed brine-containing chamber 17.

In assembling the evaporator, the refrigerant conducting tube is inserted within the brine-containing tube. I have found that tubes of 1%- diameter for the refrigerant coil and 2%, diameter for the brine coil are satisfactoryfor evaporators used in smallmachines of the household type. One end of the outer tube is sealed by a collar 14. The double-pipe coil is then formed on a suitable mandrel, with the adjacent loops of the coil in intimate contact with each other. After bein removed from the mandrel, the coils may e dipped into a suitable soldering bath in order to make the structure rigid and to maintain the loops in intimate contact. A suitable brine solution is then poured into the space between the inner and outer coils through the open end of the outer coil, after which this end is also sealed by a collar 14 which -is soldered in place. The termnbrine is used in its broadest sense and comprises not only the conventional chloride salt solutions but also alcohol and water, glycerine and water and similar mixtures.

The freezing chamber 11, which is formed by the coiled tubing, has a fixed closure plate 18 at one of its ends. rll`he plate 18 may be bent over the last loop of the coil, as shown at 19, and then soldered thereto.

A heat-conducting plate 20 may be placed in the freezing chamber 11 to provide a sup port for ice-trays. l The upper surface of this plate is flat, and the under surface 1s preferably provided with a plurality of transversely extending substantially semi-cylindrical grooves 21. The diameter of the grooves 21 is slightly larger than that of the tube 13, so that they fit snugly over the adj agent loop portions of the coil. This arrangement permits intimate thermal contact between the plate 2O and the adjacent coil, thereby increasing the effectiveness of heat transfer between the ice trays and the cooling coil. The grooves also serve to retain the plate in a fixed position within the freezing chamber when the trays are removed.

A conventional expansion valve 22 may be fixed'at the inlet end of the refrigerant coil 'It will be apparent from the foregoing descript-ion that I have provided an evaporator or heat-absorbing unit for refrigerating apparatus havoing the best features of the direct and indirect methods of cooling. The structure is comparatively light in weight, but, at the same time, has sutlicient cold-storage capacity to act as a holdover between the operating portions of the refrigerating cycle. The small amount of brine permits the evaporator to cool rapidly to its operating temperature. The exposed surface of the coil is materially greater than that present in conventional brine tanks, and the disposition of the refrigerant coil within 4the brine-containing coil permits all of the brine to be cooled uniformly, thereby, obviating the necessity of providing for brine circulation.

While I have shown and described a single embodiment of my invention, it will be apparent that other forms might be adopted, all coming within the scope of the appended claims.

I claim as my invention:

1. A cooling unit for refrigerating apparatus comprising a coiled tube for containing a brine solution, a tube disposed within the brine-containing tube for conducting refrigerant, the loops of the outer coil being in intimate contact with each other whereby to provide a freezing chamber for receiving an ice tray, and .metallic bonding means oining said coils to provide a rigid structure.

2. An evaporator comprising a coiled tube, the loops of the coil being in intimate contact with each other whereby to provide an open-ended freezing chamber, a removable metallic plate for supporting an ice tray disposed within said chamber, the under surface of said plate being provided with depressions whereby to permit the entire under surface to be in intimate thermal contact with the coil.

3. An evaporator comprising a coiled tube, the loops of the coil being in intimate contact with each other whereby to provide an open-ended freezing chamber, a removable metallic plate for supporting an ice tray disposed within said chamber, said plate having its entire under Asurface disposed in intimate thermal contact with the ad] acent supporting coil portion.

' 4. A cooling unit for refrigerating apparatus comprising a coiled tube containing a cold-retaining medium, the loops of the tube being in intimate thermal contact with each other and provided with a metallic bonding means whereby to form a rigid integral structure, a re rigerant conduit disposed inside said tube, and means for sealing the ends of the tube to the conduit.

In testimony whereof, I have hereunto subscribed my name this 6th day of May, 1929.

CARL F. NYSTROM. 

